Impact of topical ST-246® on
poxvirus dermal infection,
lesion severity/resolution and
immune responses
Principle investigator:Stacie Mosier
Faculty sponsor: Dennis Hruby, PhD
Program Director: Douglas Grosenbach, PhD
Significance:
Poxvirus disease is of medical
significance.
Currently, all troops deployed to the
Middle East and Korea are required
to obtain a smallpox vaccination.
Outbreaks of other pox-diseases
are erupting across the globe (e.g.
monkeypox, cowpox, vaccinia).
The US government and CDC
consider smallpox a potential
biological weapon.
Approximately 25% of the US
population is ineligible to receive
the vaccine.
Who can NOT get the
smallpox vaccine?
People afflicted with atopic dermatitis or
eczema.
People with immune deficiency (HIV-infected,
transplant recipients, genetic immune
deficiencies)
People receiving certain cancer therapeutics
Pregnant or breast-feeding women
Anyone residing with the above people!
Adverse events Associated with the
current approved smallpox vaccine
90% of military personnel who obtain the
smallpox vaccine will experience adverse
events.
1000 out of a million will experience severe
adverse events
50 out of a million will experience lifethreatening adverse events.
DOD, Smallpox Vaccination Program
Lane JM, et al. NEJM, 1969.
Lane JM, et al. J Infect Dis, 1970
Press release: MMWR Morbidity and Mortality
Weekly Report
May 19, 2009
www.cdc.gov/mmwr/preview/ mmwrhtml/mm58e0519a1.htm
March 5, 2009
March 27, 2009
April 27, 2009
Healthy military service member vaccinated Jan 13, 2009.
Came into hospital 1 week later with fever; diagnosed with acute
myelogenous leukemia (fast growing blood and bone marrow
cancer).
Battled progressive vaccinia until May 18, 2009.
ST-246:
Is being developed as an oral therapeutic
for the treatment of smallpox.
Low molecular weight, bioavailable
Nontoxic
Specific
Shown to be efficacious in preventing
systemic vaccinia and variola virus in
multiple animals models (e.g. mouse,
rabbit, NHP).
Shown to be safe in clinical trials.
Systemic infection results from the formation
and spread of the enveloped form of the virus,
from the point of inoculation
ST-246
In the life-cycle, the virus is
formed and released from the cell
as Extra-cellular Enveloped Virus
(EEV).
STOP
EEV: Responsible for cell-to-cell
transmission and spread
throughout host.
ST-246 prevents virus from
obtaining envelope from host.
EEV & IMV are introduced at the point
of inoculation
Since systemic problems arise from the
dissemination of the EEV at the point of inoculation:
I hypothesize that a topical formulation
of ST-246 applied to the inoculation
site
will reduce dermal infection, lesion
severity and time to recovery.
Specific Aims:
Topical Study #1
To quantitatively
assess the immune
responses elicited by
treatment with topical
formulation of ST-246
in an immune
competent model.
Topical Study #2
To evaluate the efficacy
of the topical and/or
oral treatment of ST246 in a model for
immune deficiency
Procedures: Study #1
Step 1: SKH-1 mice
anesthetized and vaccinated
VV-WR (1x106 pfu/ml)
Step 2: Mice treated
1x or 2x/ day with
1% topical solution
ST-246
Step 3: Photograph
inoculation site/
collect blood and
lesion-swab
samples to evaluate
antibody response
and viral load
Step 5:
Quantitatively
assess immune
response via flow
cytometry,
cytometric bead
array, ELISA,
neutralizing titer,
comet-inhibition, etc.
Step 4: At Day 30,
terminate study and
collect blood for
immune response
assays
Expected Outcomes:
STUDY #1
ST-246 will prevent and/or reduce
lesion severity.
Decrease viral load.
Decrease time to resolution.
Immune response will not be
inhibited.
Preliminary Data Study #1:
Procedures: Study #2
Step 1: Mice treated with
cyclophosphamide
(100mg/kg/4d) to induce
immunodeficiency
Step 2: Mice
anesthetized and
vaccinated VV-WR
(1x106 pfu/ml)
Step 3: Mice
treated 1x or
2x/day with a
topical 1%
solution and/or
oral ST-246
Step 5: Collect
blood samples and
organs/ verify
immunodeficiency
via ELISA/ measure
viral load via qPCR
Step 4: Photograph
inoculation site/
document lesion
severity and time to
resolution
Expected Outcomes:
STUDY #2
ST-246 will reduce viral load and
slow viral shedding.
Decrease lesion severity.
Ultimately, survival in this model in
unknown.
Preliminary Data Study #2:
VV-WR Tx
Topical Vehicle BID
Day 7
VV-WR Tx
Topical Vehicle BID
Day 11
VV-WR Tx
Topical Vehicle BID
Day 17
Cyclophosphamide/ VV-WR Tx
Topical Vehicle BID
Day 7
Cyclophosphamide/ VV-WR Tx
Topical Vehicle BID
Day 12
Cyclophosphamide/ VV-WR Tx
Topical Vehicle BID
Day 12
Cyclophosphamide/ VV-WR Tx
Topical Vehicle BID
Day 14
Cyclophosphamide/ VV-WR Tx
Topical Vehicle BID
Day 14
Cyclophosphamide/ VV-WR Tx
Topical Vehicle BID
Day 16
What’s the
next step?
•Optimization of dosing and
formulations. (e.g. slow-release; drug
impregnated bandages)
•Efficacy in higher order animals.
•Pharmacology
•Toxicology
Acknowledgments:
Howard Hughes Medical Institute
Dr. Dennis Hruby
Dr. Douglas Grosenbach
Dr. Aklile Berhanu
Mr. David King